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 ###Instrução: Qual classe para o valor de 1928 teve anos de fabricação de 1921/23 e classe de 1928 de BCi-21?
 ###Tabelas: CREATE TABLE general_election_results (general_election_results_id AUTO_INCREMENT PRIMARY KEY, Year VARCHAR, Candidates INT, Total votes INT, Average votes per candidate INT, % of total vote VARCHAR, Average % of vote per candidate VARCHAR, Saved Deposits INT, Number of MPs INT) CREATE TABLE singles:_15_10–5 (singles:_15_10–5_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Date VARCHAR, Tournament VARCHAR, Surface VARCHAR, Opponent VARCHAR, Score VARCHAR) CREATE TABLE pga_tour_wins_9 (pga_tour_wins_9_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, Tournament VARCHAR, Winning score VARCHAR, Margin of victory VARCHAR, Runner(s)-up VARCHAR) CREATE TABLE iron_coaches (iron_coaches_id AUTO_INCREMENT PRIMARY KEY, Class to 1928 VARCHAR, Class from 1928 VARCHAR, Seats VARCHAR, Quantity INT, Year(s) of Manufacture VARCHAR, Remarks VARCHAR) CREATE TABLE seasons (seasons_id AUTO_INCREMENT PRIMARY KEY, Season in Tamil VARCHAR, English Transliteration VARCHAR, English Translation VARCHAR, Season in Sanskrit VARCHAR, Season in English VARCHAR, Tamil Months VARCHAR, Gregorian Months VARCHAR)  
SELECT Class to 1928 FROM iron_coaches WHERE Year(s) of Manufacture = 1921/23 AND Class from 1928 = bci-21